The Cappillary action requires lots of heat in SS because most SS's resist heat flow. So I guess more heat would help.
Also bare in mind SS corrode instantly making cleaning a big issue. We clean and soak parts in Denatured Alcohol most of the time.
We use the a black paste flux on the high temp Solder That you described. You never mentioned flux.
Unless your Sculptors are going to be exposed to high temps I would use the less expensive Silver Solder. It is a lot easer to work with and the flux is not near as nasty.